Overcorrection in vertical alveolar distraction osteogenesis for dental implants

Outcomes of alveolar segmental 'sandwich' osteotomy with interpositional particulate allograft for severe vertical defects in the anterior maxilla and mandible

The purpose of this study was to report the outcomes of interpositional osteotomy with mineralized allograft in the treatment of alveolar vertical defects in preparation for implant placement. Thirteen defects (11 maxillary and two mandibular) were treated with osteotomy segments ranging in length from two to five missing teeth. The segments were positioned 5-7 mm coronally, with the gap space filled with allograft and then fixated with titanium hardware. Vertical bone augmentation was analyzed by superimposing pre- and post-surgical cone beam computed tomography images and stratified based on the length and number of missing teeth in each edentulous segment. The mean vertical bone gain was 3.7 ± 1.6 mm in the area of greatest vertical defect and the mean length of the transport segment was 20.5 ± 8.1 mm. These segments represented two-, three-, four-, or five-tooth edentulous sites; the mean vertical bone gain for these segments was 1.7 ± 0.5 mm, 3.8 ± 1.0 mm, 4.6 ± 0.9 mm, and 6.7 ± 0.0 mm, respectively. Stability of vertical height gain was found to be directly proportional to the span length of the osteotomy segment, with the largest five-tooth segment achieving the greatest gain. Vertical bone gain in two-tooth segments was minimal, indicating a moderate amount of resorption.

A Prosthetic and Surgical Approach for Full-Arch Rehabilitation in Atrophic Maxilla Previously Affected by Peri-Implantitis

Rehabilitation of atrophic maxilla with dental implants is still a challenge in clinical practice especially in cases of alveolar bone resorption due to peri-implantitis and pneumatization of the maxillary sinuses. Several surgical approaches have been employed to reconstruct the lost tissues allowing the proper tridimensional position of the implants. In this context, the aim of this case report is to describe a surgical and prosthetic approach to fully rehabilitate the atrophic maxilla with dental implants. The patient presented with unsatisfactory functional and esthetical implant-supported prosthesis with some of the implants already lost by peri-implantitis. The remaining three implants were also affected by peri-implantitis. Reversal prosthetic planning was performed, and a provisional prosthesis was fabricated and anchored in two short implants. Sinus floor augmentation procedure and onlay bone graft were then accomplished. After a healing period of 8 months, digital-guided surgery approach was performed to place the implants. Finally, a definitive prosthesis was installed. One-year follow-up has revealed stabilization of the bone tissue level, successful osseointegration, and a pleasant esthetic and functional result. A proper diagnosis and careful planning play an important role to enhance precision and to achieve patient esthetic and functional outcomes.

The animal experiment of a new optimised distraction implant

Our aim was to evaluate the function of a new optimised distraction implant. Six dogs with alveolar bone defects had a total of 18 distraction, and 6 normal, implants inserted into edentulous mandibular ridges after osteotomy. Five days after insertion the distraction implants were activated at a rate of 1 mm/2 days to achieve a distraction height of 6mm. Radiographs were taken at 0, 1, 2, and 3 months after distraction. Two dogs were killed after 1, 2, and 3 months, respectively, and 12 distraction implants taken from the different time points were evaluated by microcomputed tomographic (MicroCT) scanning and histological examination. The other 6 distraction, and the 6 normal, implants were compared after osseointegration with a fatigue test. The results showed that all the distraction implants had successfully distracted the bone to the anticipated height. Radiographs showed that the density of the regenerated bone increased steadily during the consolidation period. MicroCT showed that the regenerated bone was comparable with the native bone 3 months after distraction. Both native and regenerated bone had osseointegrated histologically by 1 month and 3 months after distraction. The experiment successfully confirmed the usefulness and feasibility of this new distraction implant, and suggests interesting clinical uses.

Simultaneous sinus lifting and alveolar distraction of a severely atrophic posterior maxilla for oral rehabilitation with dental implants

We retrospectively reviewed a new preimplantation regenerative augmentation technique for a severely atrophic posterior maxilla using sinus lifting with simultaneous alveolar distraction, together with long-term oral rehabilitation with implants. We also analyzed the regenerated bone histomorphologically. This study included 25 maxillary sinus sites in 17 patients. The technique consisted of alveolar osteotomy combined with simultaneous sinus lifting. After sufficient sinus lifting, a track-type vertical alveolar distractor was placed. Following a latent period, patient self-distraction was started. After the required augmentation was achieved, the distractor was left in place to allow consolidation. The distractor was then removed, and osseointegrated implants (average of 3.2 implants per sinus site, 80 implants) were placed. Bone for histomorphometric analysis was sampled from six patients and compared with samples collected after sinus lifting alone as controls (n = 4). A sufficient alveolus was regenerated, and all patients achieved stable oral rehabilitation. The implant survival rate was 96.3% (77/80) after an average postloading followup of 47.5 months. Good bone regeneration was observed in a morphological study, with no significant difference in the rate of bone formation compared with control samples. This new regenerative technique could be a useful option for a severely atrophic maxilla requiring implant rehabilitation.

Clinical, tomographic, and histological assessment of periosteal guided bone regeneration with cortical perforations in advanced human critical size defects

BACKGROUND

Large osseous defects that fail to heal spontaneously require ridge augmentation prior to implant placement. The periosteum can act as an effective barrier membrane. Little is known about the influence of bone decortication in enhancing guided bone regeneration outcomes.

PURPOSE

The aim of the present study was a clinical, tomographic, and histological evaluation of bone healing in large defect sites treated with cortical perforations without the use of other membranes but the periosteum.

MATERIAL AND METHODS

Ten consecutive patients undergoing ridge augmentation on the pre-maxilla due to severe bone loss were followed for an average of 35 months. Recipient sites were cortico-perforated and augmented using a combination of autogenous particulate and block grafts. The periosteal membrane was preserved and it fully covered the autografts. Histological analysis was performed in four sites from a trephine core taken at the time of implant osteotomy preparation. Tomographic assessment (computed tomography [CT] scan) at baseline and post-augmentation evaluated graft volume maintenance.

RESULTS

Recipient sites were re-entered for implant placement showing good incorporation of the grafts with minimal volume loss. Biopsy specimens showed viable bone rich in osteoblast-like cells with little or no inflammatory cells. Clinical exam revealed absence of implant transparency, mucosal recession, mobility, bleeding on probing, or suppuration at follow-up. CT scan evaluation showed an average increased bucco-lingual width at the recipient site of 8.1 mm ± 0.9 (2.5 fold) versus a 3.2 ± 0.9 at baseline (p < .0001; CI 95%: 4.04-5.71 mm), maintaining on average 98% of the augmented width at 2.9 years.

CONCLUSIONS

Periosteal preservation seems to be sufficient as a barrier membrane to protect particulate or block osseous grafts provided that good primary closure is achieved. Bone decortication may enhance clinical and histological outcomes. Graft viability (biopsy specimens) and volume maintenance (CT evaluation) remained stable 35 months post-augmentation.